Make sure the hitbox has massless enabled in its properties. When a part with mass is held by the player it can weigh the character down and cause glitching; regardless of whether or not it’s invisible.
Programmatically, you could simply do clone.Massless = true.
Also, another note, you shouldn’t assign parents using the second argument of Instance.new(); it is deprecated and can lead to weird behavior (especially if they remove the feature).
Here is Roblox staff talking about not using the second argument:
